NEW YORK — A tour bus driver who prosecutors said was all but asleep at the wheel was acquitted Friday of manslaughter and negligent homicide in a crash last year that killed 15 gamblers on their way from a Connecticut casino to New York City.

Ophadell Williams was found guilty on one count of aggravated unlicensed driving.

Williams wept and covered his face with his hands as the verdict was read. On the count which he was found guilty, the judge sentenced him to 30 days in prison, which he has served. He also was ordered to pay a fee of $500.

Williams argued throughout the trial that he had been awake and alert, and he said the crash was not the result of reckless behavior or extreme exhaustion. He said a tractor-trailer cut him off, causing him to swerve and hit a guardrail. But investigators could find no indication that had occurred.

His lawyer had said he was wracked with guilt over the crash — but not guilty of manslaughter.

“It happened as a motor vehicle accident, not as some crime,” said Williams’ lawyer, Patrick Bruno. “He tried to avoid tragedy, and tragedy occurred.”